CESTRID^. 



405 



they are carried out in the excrement. The pupa state lasts 

 from thirty to forty days, and the perfect fly appears the next 

 season from June to October. 



In Hypoderma the palpi are entirely wanting. The species are 

 either very large, or of medium size, and often quite small, cov- 

 ered with fine dense hairs. The legs are long and slender. The 

 Hypoderma hovis Degeer (Fig. 325, a, larva) or Bot-fly of the ox, 

 is black, densely pilose ; the front of the head is clirty ashen, 

 with whitish yellow hairs. The naked black thorax is twice 

 broadly banded with yellow and white ; the scutellum has 

 slight tubercles ; the abdomen is black, with a basal white or 

 yellowish band, a mesial black band, and at the end is a reddish 

 orange band of hairs. The larvas are found during the month 

 of May and in the summer in the tumors on the backs of cattle, 

 and when fully grown, which is generally in July, work their 

 way out and fall to the ground. 

 They exist in the puparium twen- 

 ty-six to thirty days, and the fly 

 appears from June to September. 

 This species is found over all the 

 civilized portions of the world. 

 Hypoderma tarandi Linn, infests, 

 in like manner, the Reindeer. 

 The genus CEstromyia is thought 

 to inhabit the Hare. CEstrus avis 

 Linn., the Sheep Bot-fly, is of a ^^s- 326. 



dirty ash color, with a fuscous ashen, banded, and obscurely 

 spotted thorax. The abdomen is marbled with yellowish and 

 white flecks, and is hairy at the end. The larva lives, during 

 April, May and June, in the frontal sinus of the sheep, and also 

 in the nasal cavity, whence it falls to the ground. It changes 

 to a pupa in twenty-four hours, and the fly appears during the 

 summer. Cuterebra has the third joint of the antennae oval or 

 elliptical and the bristle is dorsal and feathered ; the species 

 are short, very plump and hairy flies, with a proboscis elbowed 

 at the base, and with a metallic shining rounded abdomen. 

 The larvaj live in subcutaneous bots beneath the skin of vari- 

 ous animals. One species (the C. emasculator of Fitch) lives 

 in the scrotum of the squirrel, which it is known to emasculate. 



